Perhaps the most tragic war casualties are those resulting from friendly fire. Accordingly, various systems have been devised over the years to minimize the number of such incidents. For instance, aircraft have used particular flight approaches, patterns and visual beacons. Ground equipment have identified themselves as friendly through the use of identifying paints, tapes or other visual markings. However, the problem with all of these prior art approaches is that the enemy forces can easily see and duplicate them thereby rendering them useless.
Naturally, as technology improved, so did the "Identify--Friend or Foe" (IFF) systems. In particular, interrogation systems have been developed that require the targeting device to first send out an interrogation signal to a targeted object. If the targeted object is friendly, it is equipped with means to reflect the interrogation signal back to the targeting device in such a way that the targeted object is identified as friendly. Representative examples of such interrogation-reflection systems are disclosed in U.S. Pat. No. 4,049,969 issued to Salonimer et al, U.S. Pat. No. 4,361,911 issued to Buser et al and U.S. Pat. No. 4,763,361 issued to Honeycutt et al. These systems require the targeted object to first receive from, and then reflect/transmit back to, the targeting device in order to be identified as friendly. However, in chaotic battlefield conditions, it is desirable to minimize the amount of required communication between friendly objects/vehicles. In addition, these systems are not secure from enemy use if confiscated. Thus, the confiscated devices can easily be used to camouflage an enemy target as "friendly".